KR101581604B1 - Laser welding position-detecting device and welding position-detecting method - Google Patents

Abstract

The welding position detecting device for laser welding according to the present invention comprises an irradiating part 4 irradiating a welding laser beam 3 to a welded steel pipe 1 and an imaging device 5 for imaging the welding material around the welding part at predetermined time intervals , Image processing is performed to calculate the direction and amount of parallel movement of each point of the image from two or more images acquired by the imaging device 5 to specify the position of the irradiation unit 4 irradiated with the laser 3 for welding , And a display device (7) for displaying the position of the irradiating part irradiated with the welding laser specified by the image processing device (6).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a laser welding position detection device and a welding position detection method,

The present invention relates to a welding position detecting device and a welding position detecting device for laser beam welding in which a weld seam is welded with a laser heat as a concentrated heat source .

As a method of manufacturing a welded steel pipe, there is a manufacturing process in which a steel pipe is continuously supplied to form a cylindrical shape, and both ends of the steel pipe are welded together to manufacture a steel pipe product. Electric resistance welding (ERW method) has been widely used as a welding method in this manufacturing process, but in recent years, a laser welding method using laser light as a heat source has been used. A laser welding machine in which the oscillation wavelength of a semiconductor excitation laser such as a semiconductor laser and a fiber laser is shorter than that of a conventional gas oscillation laser is developed, It is difficult to reduce the efficiency due to the generation of plasma due to the interaction between the metal and the laser. As a result, the use of the laser welding method is increasingly diffused.

However, in this laser welding method, precise alignment is required so that the irradiation point of the laser always comes into contact with the abutted portion. However, in the continuous shaping process of the steel strip, the abutting position of the steel strip is liable to fluctuate depending on the conditions of the manufacturing line and the heat input conditions. Therefore, in order to accurately control the irradiation position of the laser beam, development of a method of continuously detecting the irradiation position of the laser beam in the laser welding section has been studied.

As a welding position detection method of laser welding, there is known a method of directly observing a welded portion (near the laser light irradiated portion) with a television camera to detect the center position of the butted portion and the melting paper (see Patent Document 1). In this welding position detecting method, the position of the external illumination is designed so that the welded portion is irradiated with the illumination from the external illumination and the butted portion is observed darkly but the melt is observed brightly, the brightness pattern of the observed image is binarized, The position of the center position of the paper is detected.

The imaging device captures the light reflected from the welded portion (near the laser light irradiating portion) and the plasma generated from the plasma, and a portion of the picked-up image that has a higher luminance than the surrounding portion is referred to as a laser irradiated position (Refer to Patent Document 2).

Japanese Patent Publication No. 55-18439 Japanese Patent Application Laid-Open No. 2000-263266

 B.K.P. Hron, B.G. Schunck: "Determining optical flow ", Artificial Intelligence, vol.17, pp.185-203, (1981)

However, the abutting portion of the welding material is not necessarily symmetrical due to the edge shape of the abutting portion of the welded material, the edge portion is contaminated, and the reflectance differs depending on the surface properties of the welding material. Therefore, it is difficult to stably detect the welding position only by binarizing the luminance pattern of the observed image. In addition, the shape of the fusing paper is not symmetrical, so that a sufficient detection precision can not be obtained with the welding position detection method using a binary image of the fusing paper.

Further, since the plasma is emitted by the interaction of the laser beam with the metallic vapor which is caught from the irradiation position of the laser, the emission position of the plasma and the emission position of the laser do not exactly coincide with each other, It becomes a region having a constant range. Therefore, even if image processing such as binarization or central arithmetic is performed by detecting the emission position of the plasma, the accuracy as a representative of the laser irradiation position is insufficient at the emission position of the plasma. Further, in the recent laser welding, the amount of plasma is originally reduced, which makes it difficult to detect plasma by an image.

In the method of detecting the irradiation position of the laser by the luminance calculation of the captured image, although the premise that the luminance of the irradiated position of the laser is the maximum in the captured image is placed, the diffuse reflection on the surface of the steel plate, The brightness of the irradiation position of the laser in the picked-up image can not be maximized. That is, the premise that the luminance of the irradiated position of the laser is the maximum in the picked-up image is not reliable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object of the present invention is to provide a laser welding method capable of detecting a welding position of laser welding with high reliability, without assuming that the luminance of the irradiated position of the laser is maximum in the picked- A welding position detecting device and a welding position detecting method.

In order to solve the above-described problems and to achieve the object, a welding position detecting apparatus for laser welding according to the present invention is characterized in that an irradiation section irradiating a welding laser to a welding material, By performing image processing for calculating a direction and an amount in which each point of the image is parallel transitioned from two or more images acquired by the image pickup device at a predetermined time interval, And a display device for displaying the position of the irradiation part irradiated with the welding laser specified by the image processing device.

In order to solve the above-described problems and to achieve the object, a welding position detection method of laser welding according to the present invention is a method of detecting a welding position by irradiating a laser beam onto a welding material and a welding material therearound at predetermined time intervals And an image processing step of specifying the position of the irradiation part irradiated with the welding laser by performing image processing for calculating the direction and amount of parallel movement of each point of the image from two or more images acquired by the imaging step And a display step of displaying the position of the irradiation part irradiated with the welding laser specified by the image processing step.

According to the welding position detecting device and the welding position detecting method of laser welding according to the present invention, it is possible to detect the welding position of the laser welding with high reliability, without assuming that the luminance of the irradiated position of the laser is the maximum in the captured image The effect can be demonstrated.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a configuration diagram showing a welding position detecting device for laser welding according to a first embodiment of the present invention; FIG.
2 is a functional block diagram for explaining processing performed by the image processing apparatus.
3 is a flowchart showing a welding position detection method of laser welding according to the first embodiment of the present invention.
Fig. 4 is an image of an irradiation part of a welding laser and its periphery in an actual steel pipe.
Fig. 5 is an image of an irradiated portion of a welding laser in an actual steel pipe and its periphery.
Fig. 6 is a diagram showing an optical flow distribution superimposed on the image shown in Fig. 5. Fig.
Fig. 7 is a schematic diagram showing the magnitude of the vertical component of the optical flow distribution as a distribution of shading.
8 is a schematic diagram of an average deviation degree calculated from the average of the vertical component of the optical flow distribution and the average of the vertical components of the optical flow distribution.
9 is a configuration diagram showing a welding position detecting device for laser welding according to a second embodiment of the present invention.
10 is a graph of light intensity obtained by measuring the emission spectrum of a welded portion of a steel pipe.

Hereinafter, a welding position detecting apparatus and a welding position detecting method for laser welding according to an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the welding position detecting device and the welding position detecting method for laser welding according to the embodiment of the present invention will be described based on an example of welding in the manufacturing process of the welded steel pipe, But the present invention can be suitably carried out in a manufacturing process for manufacturing the welded portion by welding while continuously supplying the welding material.

[Welding Position Detection Apparatus of First Embodiment]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a configuration diagram showing a welding position detecting device for laser welding according to a first embodiment of the present invention; FIG. 1, the welding position detecting device for laser welding according to the first embodiment of the present invention includes an irradiating portion 4 irradiating a welding laser 3 onto a butt portion 2 of a welded steel pipe 1, An image processing device 6 that synthesizes an image from an image pickup signal acquired by the image pickup device 5 and performs image processing, And a display device 7 for displaying the processed image.

The welded steel pipe 1 shown in Fig. 1 is obtained by laser-welding both edges of a steel sheet in a state of finally shaping into a cylindrical shape after a step of shaping the steel sheet into a concave shape in the width direction by the shaping means. That is, the abutted portion 2 of the welded steel pipe 1 has both edges of the steel plate butted together.

The welding laser 3 is a laser beam emitted from a laser oscillator, which is transmitted to the irradiation unit 4 through a transmission system such as a transmission tube or optical fiber combined with a mirror or the like. Of course, it is preferable that the welding laser 3 is condensed by an optical system such as a concave mirror or a convex lens, if necessary, so that the energy density of the irradiation part 4 is high.

As the imaging device 5, a camera that is generally distributed as an industrial surveillance camera such as a CCD camera or a CMOS camera is used. The image pickup device 5 selects the magnification of the objective lens or the like of the image pickup device 5 so as to pick up an image of a range of about 5 mm to 20 mm square around the irradiating portion 4 of the laser 3 for welding Respectively. For the sake of convenience of explanation, the visual field direction of the image pickup device 5 is set such that the longitudinal direction of the welded steel pipe 1 (the travel direction) is the vertical direction of the visual field and the circumferential direction of the welded steel pipe 1 is The horizontal direction of view. The field of view of the image pickup device 5 in the vertical direction can be appropriately adjusted to the lower limit (5 mm) of the acceptable range, unless the irradiation position of the laser 3 for welding is moved in the longitudinal direction of the welded steel pipe 1. It is necessary for the two consecutive images to be photographed by overlapping the same points in the visual field for the optical flow calculation to be described later. Preferably, the optical magnification and the imaging cycle are set such that at least half of the field of view in the carrying direction is overlapped. .

The image processing apparatus 6 images the image signal acquired by the image pickup apparatus 5 and calculates an optical flow distribution to be described later and calculates an optical flow distribution of the optical path distribution of the irradiation portion 4 of the laser 3 for welding And specifies the center position. The image processing apparatus 6 displays the center position of the irradiation section 4 calculated in the display device 7 and outputs information of the center position of the irradiation section 4 to another laser irradiation position drive device do.

[Optical Flow]

Here, the optical flow distribution calculated by the image processing apparatus 6 will be described.

When the abutting portion 2 of the welded steel pipe 1 is continuously observed with the image pickup device 5 fixed in the visual field, the welded steel pipe 1 in the visual field of the image pickup device 5 is moved substantially parallel And the irradiation part 4 of the laser 3 for welding shows a behavior different from that of the welded steel pipe 1. [ Therefore, if two or more images of the abutted portion 2 of the welded steel pipe 1 are captured at short time intervals, and the two images are compared to identify a portion that has moved in parallel and a portion that is not parallel, As the irradiation part 4 of the laser 3 for welding.

An optical flow method is known as a method of identifying such a portion that has moved in parallel and a portion that is not parallel (see Non-Patent Document 1). This optical flow method calculates a vector (so-called motion vector) expressing the direction and amount of parallel movement of each point of the image by numerically differentiating a temporal gradient or a spatial gradient of two images, The calculation method is implemented by a program such as OpenCV.

[Image processing apparatus]

Hereinafter, with reference to Fig. 2, an image processing apparatus 6 for specifying the position of the irradiation unit 4 of the welding laser 3 using this optical flow method will be described. Fig. 2 is a functional block diagram for explaining processing performed by the image processing apparatus 6. Fig. In the practice of the present invention, the processing performed by the image processing apparatus 6 may be implemented as software using OpenCV or the like as described above, as hardware, or as a combination of software and hardware .

2, the image processing apparatus 6 includes an image obtaining means 61, an image delaying means 62, a motion vector distribution calculating means 63, a conveying direction component calculating means 64, Means (65), difference calculating means (66), and center calculating means (67).

The image acquiring means 61 is means for imaging the image signal acquired by the imaging device 5. [ For example, if the image signal input from the image pickup device 5 to the image processing apparatus 6 is an analog signal, the image acquisition means 61 converts the image signal into a digital signal by the AD converter, 5 constitute an image frame.

The image delaying means 62 is a frame buffer for temporarily storing the image frame constituted by the image obtaining means 61. Since the optical flow method is a calculation method that uses two images captured at time intervals, the image delay means 62 temporarily stores one image or two images, thereby obtaining two images captured at time intervals Thereby enabling simultaneous processing.

The motion vector distribution calculating means 63 calculates the motion vector distribution calculating means 63 based on the two image frames temporarily stored in the image delaying means 62 or the two image frames temporarily stored in the image delaying means 62, Based on the thus constructed image frame, the optical flow distribution is calculated. That is, a vector corresponding to each point of the image is calculated by numerically differentiating the temporal or spatial gradient of the two images taken at time intervals (see Fig. 6). This vector expresses the direction and amount in which each point of the image moves in parallel. The calculation of the optical flow distribution performed by the motion vector distribution calculating means 63 may be performed for each pixel of the image frame, but the image frame may be calculated by dividing the image frame into regions of appropriate size.

The transporting direction component calculating means 64 extracts only the component in the vertical direction (the conveying direction of the welded steel pipe 1) from the optical flow distribution calculated by the motion vector distribution calculating means 63. Since the vertical component of the optical flow distribution calculated by the transporting direction component calculating means 64 is also used at the rear end, the transporting direction component calculating means 64 also has the function of temporarily storing the vertical component of the calculated optical flow distribution .

The overall average calculation means 65 averages the vertical components of the optical flow distribution calculated by the transportation direction component calculation means 64. [ That is, the overall average calculating means 65 averages the vertical component of the vector corresponding to each point of the image calculated by the carrying direction component calculating means 64 with respect to each point of the image, And a distribution corresponding to each point is calculated. The calculated average value is a value corresponding to the conveying speed of the welded steel pipe 1.

The difference calculation means 66 calculates the difference between the vertical component of the optical flow distribution calculated by the transportation direction component calculation means 64 and the average value calculated by the total average calculation means 65 for each point of the image The image obtained by this difference is referred to as an average deviation degree). That is, the difference calculating means 66 reduces the value corresponding to the conveying speed of the welded steel pipe 1 from the vertical component of the optical flow distribution calculated by the conveying direction component calculating means 64, ) Is different from the conveying movement of the sheet.

The center calculating means 67 calculates the center from the distribution of the difference value calculated by the difference calculating means 66 and calculates the center of the welded steel pipe 1 by using an irradiation portion It is a specific means. That is, since the difference value calculated by the difference calculating means 66 does not become zero, it can not be regarded as one point, and since the difference value has a certain extent, the center calculating means 67 calculates the difference The representative point is determined by calculating the center. As described above, since the part of the welded steel pipe 1, which behaves differently from the carrying movement of the welded steel pipe 1, corresponds to the irradiation part 4 of the laser 3 for welding, the representative point calculated in the center- Is the center point of the irradiation section 4 of the laser 3 for welding.

Finally, the positional information of the center point of the irradiation unit 4 of the welding laser 3 calculated by the center calculation unit 67 is transmitted to the display unit 7 and displayed on the display unit 7 It is displayed on the screen.

[Processing Flow of Welding Position Detection Method]

Next, with reference to Fig. 3, a description will be made of a welding position detecting method of laser welding according to the first embodiment of the present invention.

3 is a flowchart showing a welding position detection method of laser welding according to the first embodiment of the present invention. 3, in the first step of the welding position detecting method of laser welding according to the embodiment of the present invention, the image capturing apparatus 5 detects the position of the first image of the irradiation section 4 of the laser 3 for welding (Hereinafter referred to as " image I ") (step S1).

After the image pickup device 5 picks up the image I, the image pickup device 5 waits for a predetermined time interval (step S2), and the image pickup device 5 picks up the second image of the irradiation part 4 of the welding laser 3 (Hereinafter referred to as " image II ") (step S3).

Thereafter, the image I and the image II are transmitted to the image processing apparatus 6, and the motion vector distribution calculating means 63 of the image processing apparatus 6 calculates the optical flow distribution from the image I and the image II S4). The transport direction component calculating means 64 of the image processing apparatus 6 calculates the vertical direction component of the optical flow distribution (Step S5), and the overall average calculating means 65 of the image processing apparatus 6 calculates the optical flow And calculates the average of the entire image in the vertical direction component of the distribution (step S6). Then, the difference calculating unit 66 of the image processing apparatus 6 calculates the average deviation from the average of the vertical component of the optical flow distribution and the vertical component of the optical flow distribution (step S7).

Finally, the center calculating means 67 of the image processing apparatus 6 calculates the two-dimensional center from the average deviation degree to specify the center point of the irradiating section 4 of the welding laser 3 (step S8).

Example

Hereinafter, the welding position detection method of laser welding according to the embodiment of the present invention described above will be described with reference to the image of the irradiation section 4 of the welding laser 3 in the actual welded steel pipe 1.

Figs. 4 and 5 are two consecutive frames of an image of the irradiating portion 4 of the welding laser 3 and its vicinity in the actual welded steel pipe 1. Fig. The time interval of the images of two consecutive frames shown in Figs. 4 and 5 is 1/30 second, which is the same as the video rate. However, the amount of movement in the visual field at the same point of the steel pipe in this embodiment is the shape of the welded steel pipe It is sufficiently smaller than the field of view in the transport direction and satisfies the imaging conditions necessary for the optical flow calculation. The image shown in Fig. 4 corresponds to the image I in the above-mentioned processing flow, and the image shown in Fig. 5 corresponds to the image II in the above-mentioned processing flow.

4 and 5, the shape of the welded steel pipe 1 itself indicated by the arrow A moves along the conveyance of the welded steel pipe 1, while the shape of the welded laser pipe 1 indicated by the arrow B The position of the irradiating unit 4 is not moved.

Fig. 6 is a diagram showing the optical flow distribution calculated from the images shown in Figs. 4 and 5, superimposed on the image shown in Fig. 5. Fig. The calculation unit used in the calculation of the optical flow distribution shown in Fig. 6 is an area obtained by dividing into 32 in the horizontal direction and 24 in the vertical direction of the image shown in Figs.

6, the portion of the welding laser 3 other than the irradiation portion 4 becomes a vector in the same direction caused by the parallel movement due to transportation. However, as shown in Fig. 6, The portion has a small vector size and a different direction.

Fig. 7 is a schematic diagram showing the magnitude of the vertical component (Vy) of the optical flow distribution shown in Fig. 6 as a distribution of shading. 7, the concentration of the density distribution (that is, the magnitude of Vy) of the welded steel pipe 1 other than the abutting portion 2 is substantially uniform, while the position of the irradiation portion 4 of the welding laser 3 is Extremely high concentration (in short Vy is small).

Fig. 8 is a schematic diagram of the average deviation calculated from the average of the vertical component of the optical flow distribution shown in Fig. 6 and the average of the vertical components of the optical flow distribution. 8, the abutting portion 2 of the welded steel pipe 1 also has a certain value. However, since the irradiation portion 4 of the laser 3 for welding has a certain degree of deviation, Is extremely high. Therefore, it can be seen that the irradiation unit 4 of the laser 3 for welding can be specified by calculating the two-dimensional center from the mean deviation chart shown in Fig.

As described above, in the welding position detecting device for laser welding according to the first embodiment of the present invention, the welding portion 4 irradiated with the welding laser beam 3 to the welded steel pipe 1 and the welded steel pipe 1 around the irradiated portion 4 By performing image processing for calculating directions and amounts of respective points of the image moved in parallel from two or more images acquired by the image pickup device 5 by performing image processing for obtaining images at intervals of time, An image processing apparatus 6 for specifying the position of the irradiation section 4 irradiated with the welding laser 3 specified by the image processing apparatus 6 and a display device 7 for displaying the position of the irradiation section irradiated with the welding laser 3 specified by the image processing apparatus 6, It is possible to detect the welding position of laser welding with high reliability without assuming that the luminance of the irradiation position of the laser is the maximum in the picked-up image.

[Welding Position Detection Apparatus of Second Embodiment]

9 is a configuration diagram showing a welding position detecting device for laser welding according to a second embodiment of the present invention. 9, the welding position detecting device for laser welding according to the second embodiment of the present invention includes an irradiating part 4 irradiating a welding laser 3 onto an abutting part 2 of a welded steel pipe 1, An image processing device 6 that synthesizes an image from an image pickup signal acquired by the image pickup device 5 and performs image processing, A short wavelength light source 8 for illuminating the irradiating unit 4 and a transmission unit 7 for transmitting the wavelength of the short wavelength light source 8 disposed at the front end of the image pickup device 5, And a band-pass filter (9) having characteristics.

As shown in Fig. 9, the welding position detecting device for laser welding according to the second embodiment of the present invention has many components common to the welding position detecting device for laser welding according to the first embodiment of the present invention. Therefore, in the welding position detecting device for laser welding according to the second embodiment of the present invention, the description of the common components will be omitted.

The short wavelength light source 8 for illuminating the irradiation unit 4 is an optical source for emitting short wavelength light in the range of 800 nm to 900 nm. The short-wavelength light source 8 may be a wavelength-limited white light source with a band-pass filter, but it is preferable to use a semiconductor laser light source because small and strong light can be irradiated. For example, an infrared laser diode of 808 nm can be used as a light source for emitting short wavelength light in a range from 800 nm to 900 nm.

On the other hand, a band filter 9 having a transmission characteristic that transmits the wavelength of the short wavelength light source 8 disposed at the front end of the image pickup device 5 can be a commonly used filter such as a thin film dielectric type interference filter have. When a white light source whose wavelength is limited by a bandpass filter is used as the short wavelength light source 8 and the bandpass filter 9 disposed at the front end of the image pickup device 5 is a filter of the same kind , And has the transmission characteristic that transmits the wavelength of the short wavelength light source 8 is automatically satisfied.

Hereinafter, with reference to Fig. 10, the reason why the short wavelength light source 8 is preferably a light source that emits short wavelength light having a wavelength of 800 nm to 900 nm is described.

10 is a graph of light intensity obtained by measuring the emission spectrum of the welded portion of the welded steel pipe 1. As shown in Fig. As shown in Fig. 10, a disturbing luminescence phenomenon occurs in welding. Plasma and welding fumes are factors that cause these luminescent phenomena. Further, the plasma generates extraneous light by interaction between the metal vapor and the laser light stuck to the laser irradiation position, and the welding fume is fine mineral dust generated by cooling the evaporated metal generated in the atmosphere in the atmosphere, Also generates disturbance light by the interaction of laser light. As shown in Fig. 10, there are many components whose wavelengths are 800 nm or less in emission wavelength of these disturbance light.

On the other hand, the imaging sensitivity of a CCD camera or the like used as the imaging device 5 is lowered in an infrared ray region of 900 nm or more. Thus, in the welding position detecting device for laser welding according to the second embodiment of the present invention, a light source that emits short wavelength light having a wavelength of 800 nm to 900 nm is used as the short wavelength light source 8.

The welding position detection method of laser welding using the welding position detection device for laser welding according to the second embodiment of the present invention is characterized in that the welding position detection of laser welding using the laser welding position detection device according to the first embodiment And therefore, they are omitted here.

As described above, in the welding position detecting device for laser welding according to the second embodiment of the present invention, the welding portion 4 irradiated with the welding laser 3 on the welded steel pipe 1 and the welded steel pipe 1 around the irradiated portion 4, By performing image processing for calculating directions and amounts of respective points of the image moved in parallel from two or more images acquired by the image pickup device 5 by performing image processing for obtaining images at intervals of time, An image processing apparatus 6 for specifying the position of the irradiation section 4 irradiated with the welding laser 3 specified by the image processing apparatus 6 and a display device 7 for displaying the position of the irradiation section irradiated with the welding laser 3 specified by the image processing apparatus 6, A short wavelength light source 8 for irradiating the irradiated portion 4 and the welded steel pipe 1 around the irradiated portion 4 with a short wavelength light in the range of 800 nm to 900 nm and a short wavelength light source 8 for transmitting the wavelength of the short wavelength light source 8 (5) and an irradiation unit (4) The provision of the band filter 9 disposed thereon makes it impossible to set the maximum luminance of the irradiated position of the laser in the captured image and to suppress the influence of disturbances such as plasma and welding fumes, Can be detected.

Industrial availability

As described above, the welding position detecting device and the welding position detecting method of laser welding according to the present invention are useful for detecting the welding position of laser welding, and particularly suitable for detecting the welding position of laser welding in the production of welded steel pipe Do.

1: welded steel pipe
2:
3: Laser welding
4:
5:
6: Image processing device
7: Display device
8: short wavelength light source
9: Bandpass filter
61: Image acquiring means
62: image delay means
63: Motion vector distribution calculating means
64: conveying direction component calculating means
65: total average calculating means
66: Difference calculation means
67: central calculation means

Claims (4)

An image pickup device for picking up an irradiating part irradiated with a laser for welding to a welding material transported and moved and a welding material around the irradiating part at predetermined time intervals,
An image processing for calculating a direction and an amount in which each point of the image is parallel moved from two or more images acquired by the image pickup device is performed, and based on the calculated direction and amount of each of the points, An image processing apparatus for extracting a part having a different behavior from the moving part to specify the position of the irradiation part irradiated with the welding laser,
And a display device for displaying the position of the irradiation part irradiated with the welding laser specified by the image processing device. The method according to claim 1,
A short wavelength light source for irradiating a short wavelength light in the range of 800 nm to 900 nm to the irradiation part and the welding material around the irradiation part,
Further comprising a band filter disposed between the imaging device and the irradiating unit and having a transmission characteristic that transmits a wavelength of the short wavelength light source. 3. The method according to claim 1 or 2,
The image processing apparatus includes:
Motion vector distribution calculating means for calculating, from two or more images acquired by the image pickup apparatus, a distribution in which directions of respective points of the image are parallel moved and a positive distribution;
A conveying direction component calculating means for calculating a conveying direction component of the weld material from a direction in which each point is moved in parallel and a positive amount;
Total average calculating means for calculating an average of all of the images of the welding direction of the welding material in a direction and a positive distribution in which the points are moved in parallel,
Difference means for calculating an average deviation by calculating a difference between a direction and a positive distribution of each point in parallel movement and a conveying speed component of the weld material,
And an irradiating unit specifying means for specifying a position of the irradiating portion irradiated with the welding laser from the average deviation. An image pickup step of picking up an irradiation part irradiated with a laser for welding on a welding material transported and moved and a welding material around the irradiation part,
Image processing is performed to calculate the direction and amount of parallel movement of each point of the image from the two or more images acquired by the imaging step, and based on the calculated direction and amount of the parallel movement of the respective points, An image processing step of specifying a position of an irradiation part irradiating the welding laser for extracting a part having a different behavior from the moving part,
And a display step of displaying a position of an irradiation part irradiated with the welding laser specified by the image processing step.

Images